Hydraulic copying device for lathes



4, 1953 o. VON ZELEWSKY 2,645,084

HYDRAULIC COPYING DEVICE FOR LATHES Filed April 18, 1950 .IN VENTO l: tt va van Ze/eusK q OMMAA ATTO ILN EB S Patented July 14, 1953 HYDRAULIC COPYING DEVICE LATHES Ottomar von Zelewsky, Neuhausen am 'Rheinfall, 1 Switzerland, assignor to Georg Fisher Aktiengesellschaft, Schalfhausen, Switzerland, a company of Switzerland Application April 18, 1950, Serial No. 156,537

In Switzerland November 30, 1949 g This invention relates to a copying lathe and relates more particularly to a lathe comprising an hydraulic system for the operation of the tool. Lathes of this type are provided with a follower which cooperates with a steeringpin and which regulates the pressure of a fluid flowing continuously on both sides of a differential piston located in a slide. The follower moves in engagement with a template or prototype held upon suitable supports and causes corresponding movements of a tool-carrying casing slidable upon the aforesaid slide.

An object of the present invention is the provi sion of an hydraulic system operatively connecting the follower with the tool holder which is eflicient and durable in operation. I

Other objects of the present invention will appear more clearly from the following specification.

The objects of the present invention may be carried out through the provision of an hydraulic system wherein inflow and outflow of the pressure medium in a chamber located above the operating pin which is engaged by the follower is regulated through the movements of said regulating pin.

The invention will appear more clearly from the following detailed description, when taken in connection with the accompanying drawing showing, by way of example, a preferred embodiment of the inventive idea.

The drawing is a diagram illustrating the hydraulic system of the lathe in section, and other parts in side elevation.

The copying lathe illustrated diagrammatically in the drawing includes a frame I carrying a 1011- gitudinal track 2 and a carriage 3 which is moved upon the track 2 by any suitable means not shown in the drawing. A work piece I is supported 6 Claims. (Cl. 60-52) A container I! for the'pressure fluid is carried by the casing-3 which supports a pump I8 communicating with'the interior of the container I1 and adapted to transmit fluid through a pipe I9 into the annular space 3i I I A steering casing 25, which is partly constructed as a difierential piston, is located within the casing I0 and is adjustably connected therewith by a threaded spindle 25, one end of which is screwed into a corresponding threaded opening; of the casing 26 while the other end extends through the top of the casing I0 and is firmly connected with a hand wheel 24 located outside of the casing l0.

The follower 21 is swingably mounted upon a pivot 28 carried by the casing 26. The inner end of the follower 2'! is in engagement with a steering piston or valve pin 29 which is reciprocably mounted in a bore or space 45 provided in the casing 26. In the example illustrated the valve pin 29 consists of two. parts which are slidable in the space 45 and which are joined by a thinner rod 29a. Due to this arrangement a chamber 32 is formed within the casing 26 which may be in along its axis 4 between a headstock 5 and a tailstock 6. The carriage 3 is slidable in directions parallel to the axis 4. The carriage 3 carries guides 8 and 9 which are firmly mounted thereon, and upon which slides a carriage or slide ID. The slide is integral with a tool holder I5 which carries a tool It used to shape the work piece4 in conformity with the outlines of a template23.

communication with a passage 4| or a passage 3|; depending upon the position of the valve pin 29. The passages 3| and 4| are formed in'the casing 26. The passage 3I leads from the chamber 32 toa space 33 located between the casing 26 and an inner wall ofthe casing ID.

A threaded needle-valve 34 is carried by the casing 26. andextends between the space33 and the space-behind the valve pin 29. A passage 45a extends between the needle. valve and the passage3I. c g .7

A spring is located within the space 45 and engages the bottom of the space 45 and the bottom of the pin 29, pressing the pin againstthe follower 21. I

The needle valve 34 is used to regulate the flow of the pressure-fluid between passages 3| and 45.

The conduit I9 leadsvto an annular space 35 provided within thecasing I0 around the piston [2. Furthermore, the conduit I9'is in communication with a pressure-regulating valve 38 which also operates as a relief valve, and which is pressed upwardly by a spring 31. A chamber 38a located directly above the valve 36 -ma-ycommunicate with a passage-'38 formed in the piston I2, and communicating with avspace 44 efitending between the'piston I2 andthecas- Another passage 39 connects the space 44 with anyannular space 40 extending around the casez h- :v c. 1

The passage il which is in communication 3 with the space 43, leads to an edge 43 provided in the valve pin 29.

A conduit 42a is formed in the casing it! and connects the space 33 with a conduit 42 by means of which fluid returned to the container ll.

This hydraulic copying device is operated according to the following principles:

The pump l8 operates continuously so that there is a constant flow of the hydraulic medium. In the course of the movement of the slide or casing 3 the follower 2'! slides upon the surfaces of the template 23. Since the follower 21 is in contact with the valve pin 29, a swinging movement of the follower 21 will be transmitted to the valve pin 29, the position of which will regulate the division of pressure in the space 44 above the piston 12 and the space 35 below the piston I2. It should be noted that the movements of the pin [2 are in the order of a few hundredths of one millimeter in any one direction and yet they sufiice to provide a proper division of the pressure of the hydraulic fluid, whereupon the pin moves into its middle position.

The pump I8 pumps the pressure medium out of the container [1 through the conduit [9 into the annular space 35 extending around the piston I2. At the same time fluid will flow to the chamber 38a and will be accumulated there until its pressure becomes greater than the pressure of the spring 31. Then the valve 3'! is opened so that the pressure medium can flow into the channel 38 and thence into the space 44, the passage 39, the space 40 and the passage 4|.

Should further movement be blocked by the valve pin 29 the pressure in the space 38a will 1.

continue to grow until the spring 31 is compressed still further. Then the valve 36 will operate as a relief or overflow valve and will allow the return flow of the pressure fluid through the conduit 31a into the container ll. Thus, the valve 36 maintains an adjustable, constant pressure in the annular chamber 35 during the copying operation. It should be noted that the fluid upwardly along with the casing l0. Fluid pressure will be balanced and the upward movement will cease when the follower 21 is moved into engagement with the template 23. As the result of this engagement with the template the follower 21 will swing about its pivot 28 so that the valve pin 29 will move upwardly, thereby compressing the spring 30. The edge 43 of the valve pin 29 will move upwardly so that connection will be provided between the channel 4| and the channel 3|. Fluid will then flow through the channel 3|, the space 33 and the conduits 42a and 42 into the container [1. This will produce a drop in pressure in the space 44 located above the piston l2 and since pressure in the chamber is maintained, the casing I0 will move downwardly.

As already stated, the extent of the movements of the valve pin 29 is very small so that the edge 43 moves back into the position shown in the 4 drawing and the balance of the system is quickly restored.

The needle valve 34 is utilized to dampen possible oscillations of the casing l0 and to make these oscillations aperiodic. Such oscillations may be caused by friction among the various parts, effects of the forces asserted by the tool l6 and changeable flow properties of the pressure fluid utilized in the system. The needle valve 34 will operate to choke the inflow and the outflow of the pressure medium situated above the valve pin 29 in the space 45, thereby preventing conditions at the edge 43 which would disturb the equilibrium and result in the aforesaid oscillations.

It is apparent that the example shown above has been described solely by way of illustration and not by way of limitation, and that it is subject to many variations and modifications without departing from the scope or intent of the present invention. All such variations and modiflcations are to be included within the scope of the present invention.

What is claimed is:

1. A hydraulic copying device, comprising, a body; a piston connected with said body, an actuator pivotally mounted in said piston, a steering pin movably mounted in said piston and pressing against said actuator, a regulating valve operatively connected with said steering pin, said piston having a chamber formed therein which is located above said actuator and is in communication with said valve, means pumping fluid to said chamber, and means connected with said valve for removing the pumped fluid when the valve is opened by said actuator.

2. A hydraulic copying device, comprising, a body; a piston connected with said body, an actuator pivotally mounted in said piston, a steering pin movably mounted in said piston and pressing against said actuator, a regulating valve operatively connected with said steering pin, said piston having a chamber formed therein which is located above said actuator and is in communication with said valve, means pumping fluid to said chamber, means connected with said valve for removing the pumped fluid when the valve is opened by said actuator, and a common fluid container for the first-mentioned and secondmentioned means.

3. A hydraulic copying device, comprising, a body; a piston connected with said body, an actuator pivotally mounted in said piston, a steering pin movably mounted in said piston and pressing against said actuator, a regulating valve operatively connected with said steering pin, said piston having a chamber formed therein which is located above said actuator and is in communication with said valve, means pumping fluid to said chamber, means connected with said valve and constituting a passage for removing the pumped fluid when the valve is opened by said actuator and an adjustable needle valve threaded into said Piston and extending into said passage.

4. A hydraulic copying device, comprising, a body; a piston connected with said body, an actuator pivotally mounted in said piston, a steering pin movably mounted in said piston and pressing against said actuator, a regulating valve operatively connected with said steering pin, a fixed differential piston located adjacent the first-mentioned piston within said body, a pump communicating with the second-mentioned piston, and means within the second-mentioned piston for transmitting fluid pumped by said pump to a space between said body and the second-mentioned piston, the first-nentioned piston having formed therein a passage connecting said space with said valve, and another passage connecting said valve with a space between said body and the first-mentioned piston, said body having an exhaust passage formed therein and connected with the second-mentioned space.

5. A hydraulic copying device, comprising, a body; a piston connected with said body, an actuator being pivotally mounted in said piston, a steering pin movably mounted in said piston and pressing against said actuator, a regulating valve operatively connected with said steering pin, a fixed differential piston located adjacent the first-mentioned piston within said body, a pump communicating with the second-men tioned piston, a relief valve within the secondmentioned piston and connected with said pump for transmitting fluid pumped by said pump to a space between said body and the second-mentioned piston, the first-mentioned piston having formed therein a passage connecting said space with said valve, and another passage connecting said valve with a space between said body and the first-mentioned piston, said body having an exhaust-passage formed therein and connected with the second-mentioned space, an exhaust pipe connected with said exhaust passage, and a fluid container communicating with said pump and said exhaust pipe.

6. A hydraulic copying device, comprising, a

body; a piston connected with said body, an actuator pivotally mounted in said piston, a steering pin movably mounted in said piston, said piston having a valve chamber formed therein, a valve body movably mounted in said valve chamber, a spring within said valve chamber pressing said steering pin against said actuator, said piston References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,437,570 Von Zelewsky Mar. 9, 1948 2,474,134 Waterson June 21, 1949 

